Re: [PATCH 03/19] ARM64 / ACPI: Introduce lowlevel suspend function

From: Sudeep Holla
Date: Mon Jul 28 2014 - 14:28:30 EST

On 24/07/14 14:00, Hanjun Guo wrote:
From: Graeme Gregory <graeme.gregory@xxxxxxxxxx>

acpi_wakeup_address is used on x86 as the address bios jumps into
when machine wakes up from suspend. As arm64 does not have such a
bios this mechanism will be provided by other means. But the define
is still required inside the acpi core.

Introduce a null stub for acpi_suspend_lowlevel as this is also
required by core. This will be filled in when standards are
defined for arm64 ACPI global power states.

Reviewed-by: Grant Likely <grant.likely@xxxxxxxxxx>
Signed-off-by: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
arch/arm64/include/asm/acpi.h | 12 ++++++++++++
arch/arm64/kernel/acpi.c | 7 +++++++
2 files changed, 19 insertions(+)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index e8581ea..44b617f 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -36,6 +36,18 @@ static inline bool acpi_has_cpu_in_madt(void)
return 1;

+/* Low-level suspend routine.
+ *
+ * ACPI S-states for ARM64 have to be defined
+ * and approved before doing anything else, maybe
+ * we need update the ACPI spec, here we
+ * just introduce function and macro needed by
+ * ACPI core as IA64 did, and revisit them when
+ * the spec is ready.
+ */
+extern int (*acpi_suspend_lowlevel)(void);
+#define acpi_wakeup_address 0

While I understand that this is temporary solution, but will this be
sufficient to make sure we don't enter acpi_suspend_enter ?

A brief look at acpi_suspend_enter showed access to write to
ACPI_BITREG_SCI_ENABLE which might just explode. But if you are sure that
it will not be executed, then it should be fine for now.


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